Asset Oriented Modeling (AOM)

- Step by Step (4) -

Normalization

We make sure that:

• Asset types are primitive, i.e. their properties do not contain assets that could be modeled as independent asset types. 
  
  

• Asset types are minimal, i.e. they do not contain redundant properties, meaning none of their properties can be derived from other properties.
  
  

• Asset types should have a key. Keys must be minimal, i.e. they must consist of the smallest set of properties that can uniquely identify an instance.
  
  

• The model must be complete, i.e. other assets contained in the given scenario can be derived from the defined asset types.
  
  

• Asset types must not be redundant, i.e. none of the defined asset types can be derived from other asset types.
  
  

• All asset types must have a unique meaning.

Partitioned Normal Form

The advantage of PNF-assets is that their structure can be transformed (for example during schema evolution) without loss of information. Especially, if we plan to store assets in relational databases, PNF is essential. Relational technology requires to fragment complex structures into flat relational tables. Keys that span complex structures are lost during such a transformation to First Normal Form (1NF).

Most asset types in our example are in PNF as most of them have an atomic property that acts as primary key.

The asset type "person", however, is not in PNF. It does not have an atomic property which could act as key. The only property is the complex property "name". To transform this asset into PNF, we have two options:

• Resolve name(first,middle?,last) into three separate properties: firstName, middleName?, lastName. However, we would loose structural information by this: The fact that all three properties belong together is now only visible in the name pattern.
• Introduce a new atomic property as a key such as socialSecurityNumber. In this case, person would be in PNF: the atomic property socialSecurityNumber is a key, and the complex complex property name is itself in PNF since it only has atomic sub-properties.

In some cases, however, PNF is too strict. Therefore, PNF is only a "should" and not a "must" for AOM normalization.

Contact: info@aoModeling.org